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// Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
part of utilslib;
/**
* General purpose date/time utilities.
*/
class DateUtils {
// TODO(jmesserly): localized strings
static const WEEKDAYS = const [
'Monday',
'Tuesday',
'Wednesday',
'Thursday',
'Friday',
'Saturday',
'Sunday'
];
static const YESTERDAY = 'Yesterday';
static const MS_IN_WEEK =
DateTime.DAYS_PER_WEEK * Duration.MILLISECONDS_PER_DAY;
// TODO(jmesserly): workaround for missing DateTime.fromDate in Dartium
// Remove this once that is implemented. See b/5055106
// Parse a string like: "Mon, 27 Jun 2011 15:22:00 -0700"
static DateTime fromString(String text) {
final parts = text.split(' ');
if (parts.length == 1) {
return _parseIsoDate(text);
}
if (parts.length != 6) {
throw 'bad date format, expected 6 parts: $text';
}
// skip parts[0], the weekday
int day = int.parse(parts[1]);
final months = const [
'Jan',
'Feb',
'Mar',
'Apr',
'May',
'Jun',
'Jul',
'Aug',
'Sep',
'Oct',
'Nov',
'Dec'
];
int month = months.indexOf(parts[2], 0) + 1;
if (month < 0) {
throw 'bad month, expected 3 letter month code, got: ${parts[2]}';
}
int year = int.parse(parts[3]);
final timeParts = parts[4].split(':');
if (timeParts.length != 3) {
throw 'bad time format, expected 3 parts: ${parts[4]}';
}
int hours = int.parse(timeParts[0]);
int minutes = int.parse(timeParts[1]);
int seconds = int.parse(timeParts[2]);
// TODO(jmesserly): TimeZone is not implemented in Dartium. This ugly
// hack applies the timezone from the string to the final time
int zoneOffset = int.parse(parts[5]) ~/ 100;
// Pretend it's a UTC time
DateTime result =
new DateTime.utc(year, month, day, hours, minutes, seconds, 0);
// Shift it to the proper zone, but it's still a UTC time
result = result.subtract(new Duration(hours: zoneOffset));
// Then render it as a local time
return result.toLocal();
}
/** Parse a string like: 2011-07-19T22:03:04.000Z */
// TODO(jmesserly): workaround for DateTime.fromDate, which has issues:
// * on Dart VM it doesn't handle all of ISO 8601. See b/5055106.
// * on DartC it doesn't work on Safari. See b/5062557.
// Remove this once that function is fully implemented
static DateTime _parseIsoDate(String text) {
void ensure(bool value) {
if (!value) {
throw 'bad date format, expected YYYY-MM-DDTHH:MM:SS.mmmZ: $text';
}
}
bool isUtc = text.endsWith('Z');
if (isUtc) {
text = text.substring(0, text.length - 1);
}
final parts = text.split('T');
ensure(parts.length == 2);
final date = parts[0].split('-');
ensure(date.length == 3);
final time = parts[1].split(':');
ensure(time.length == 3);
final seconds = time[2].split('.');
ensure(seconds.length >= 1 && seconds.length <= 2);
int milliseconds = 0;
if (seconds.length == 2) {
milliseconds = int.parse(seconds[1]);
}
return new DateTime(
int.parse(date[0]),
int.parse(date[1]),
int.parse(date[2]),
int.parse(time[0]),
int.parse(time[1]),
int.parse(seconds[0]),
milliseconds);
}
/**
* A date/time formatter that takes into account the current date/time:
* - if it's from today, just show the time
* - if it's from yesterday, just show 'Yesterday'
* - if it's from the same week, just show the weekday
* - otherwise, show just the date
*/
static String toRecentTimeString(DateTime then) {
bool datesAreEqual(DateTime d1, DateTime d2) {
return (d1.year == d2.year) &&
(d1.month == d2.month) &&
(d1.day == d2.day);
}
final now = new DateTime.now();
if (datesAreEqual(then, now)) {
return toHourMinutesString(new Duration(
days: 0,
hours: then.hour,
minutes: then.minute,
seconds: then.second,
milliseconds: then.millisecond));
}
final today = new DateTime(now.year, now.month, now.day, 0, 0, 0, 0);
Duration delta = today.difference(then);
if (delta.inMilliseconds < Duration.MILLISECONDS_PER_DAY) {
return YESTERDAY;
} else if (delta.inMilliseconds < MS_IN_WEEK) {
return WEEKDAYS[getWeekday(then)];
} else {
// TODO(jmesserly): locale specific date format
String twoDigits(int n) {
if (n >= 10) return "${n}";
return "0${n}";
}
String twoDigitMonth = twoDigits(then.month);
String twoDigitDay = twoDigits(then.day);
return "${then.year}-${twoDigitMonth}-${twoDigitDay}";
}
}
// TODO(jmesserly): this is a workaround for unimplemented DateTime.weekday
// Code inspired by v8/src/date.js
static int getWeekday(DateTime dateTime) {
final unixTimeStart = new DateTime(1970, 1, 1, 0, 0, 0, 0);
int msSince1970 = dateTime.difference(unixTimeStart).inMilliseconds;
int daysSince1970 = msSince1970 ~/ Duration.MILLISECONDS_PER_DAY;
// 1970-1-1 was Thursday
return ((daysSince1970 + DateTime.THURSDAY) % DateTime.DAYS_PER_WEEK);
}
/** Formats a time in H:MM A format */
// TODO(jmesserly): should get 12 vs 24 hour clock setting from the locale
static String toHourMinutesString(Duration duration) {
assert(duration.inDays == 0);
int hours = duration.inHours;
String a;
if (hours >= 12) {
a = 'pm';
if (hours != 12) {
hours -= 12;
}
} else {
a = 'am';
if (hours == 0) {
hours += 12;
}
}
String twoDigits(int n) {
if (n >= 10) return "${n}";
return "0${n}";
}
String mm =
twoDigits(duration.inMinutes.remainder(Duration.MINUTES_PER_HOUR));
return "${hours}:${mm} ${a}";
}
}